The present invention relates in general to a communication apparatus using a SIP protocol, and, more particularly, the invention relates to a QoS (Quality of Service) control method for routers on a network, based on user preference information.
In peer-to-peer communication, in which a one-to-one connection is established between corresponding end users, a session between user communication terminals is established by a session control protocol typified by the Session Initiation Protocol (SIP) specified in the Request for Comments (RFC) 3261, a Recommendation for Internet Standards, and a communication of real-time data, such as audio and video, is performed in the session. In the use of SIP, a SIP server that relays session control messages locates a callee's terminal and effects the management of session information, such as terminal information and peer-to-peer communication information. Besides, to satisfy calling and called user requirements, session control for the users is performed, based on a database, which is called a user preference.
On the other hand, network operators, such as communication carriers and Internet Service Providers (ISPs), rely on communication quality assurance policies and routing control policies, which are generally called policies. The policies are managed by a policy server in an integrated manner, and a great number of nodes constituting a network and the QoS of the network are controlled by the policy server. A known protocol for policy servers is, e.g., a Common Open Policy Service (COPS) protocol specified in RFC 2478, a Recommendation for Internet Protocol, developed by the Internet Engineering Task Force (IETF) and published by the Internet Architecture Board (IAB).
The following method for priority control of packets in a particular flow on a network is known. For example, a relay node, called an edge node, which is located on the boundary of the network, classifies the packets flowing in the network into a plurality of classes of priority control; and, in the header of each packet flowing in, it sets one of “Diffserv Code Point (DSCP)” values that correspond to the classes of priority control for the packets. A relay node, called a core node, which is located at an inner point of the network, performs priority control and forwarding of the packets it has received, according to the DSCP value included in the header of every packet it received and in compliance with a predetermined rule. This technique is called Differentiated Services (Diffserv) and, e.g., as in Internet Protocol (IP) telephony, it is used to decrease a delay in transferring real-time packets, such as voice packets, and video packets on the IP network, e.g., such as an IP telephony network.
The constitutions of a known session QoS control apparatus and a known policy server are shown in FIG. 10. The session QoS control apparatus comprises a session management database 150 and a session information analysis means 110. The policy server comprises a user communication terminal and router management database 170 and a means for communication with a router 130.
As the network scale expands and VoIP users grow, in the method in which QoS information for all sessions of the VoIP communication terminals must be set on the nodes beforehand, the loads on the nodes will increase, resulting in an increase of the delay in relaying real-time packets. Also, this method is unable to change a QoS information setting or the like in real time, responsive to a change in the states of VoIP users. Because the SIP is a Layer 7 technique, there is also a problem in which the SIP server is incapable of direct control over the QoS of the network.
Furthermore, because the policy server cannot detect the start and end of a session communication between VoIP communication terminals, the policy server's operator must set a policy for each node in response to the start and end of VoIP communication, a change of the user state, and a change of the session condition. However, with expansion of the network, a frequent policy setting will be needed, and a situation where the operator's setting operation cannot keep up with the need will occur.